fix(cloud-task): drop unsafe append in log-gap inconsistency path (#2102)

Author: sampennington

apps/code/src/renderer/features/sessions/service/service.test.ts

@@ -1527,7 +1527,7 @@ describe("SessionService", () => {
       expect(mockSessionStoreSetters.appendEvents).not.toHaveBeenCalled();
     });
 
-    it("processes a pending cloud log gap after active reconciliation finishes", async () => {
+    it("queues a pending cloud log gap when stale fetches can't fill it, without appending", async () => {
       const service = getSessionService();
       let sessionState = createMockSession({
         taskRunId: "run-123",
@@ -1628,38 +1628,18 @@ describe("SessionService", () => {
       });
       resolveFirstLocalLogs("");
 
+      // The pending request must drain after the in-flight one resolves —
+      // verify the second readLocalLogs call eventually happens.
       await vi.waitFor(() => {
-        expect(mockSessionStoreSetters.appendEvents).toHaveBeenCalledTimes(2);
-      });
-      expect(mockSessionStoreSetters.appendEvents).toHaveBeenNthCalledWith(
-        1,
-        "run-123",
-        [
-          expect.objectContaining({
-            message: expect.objectContaining({
-              params: { entry: firstEntry },
-            }),
-          }),
-        ],
-        6,
-      );
-      expect(mockSessionStoreSetters.appendEvents).toHaveBeenNthCalledWith(
-        2,
-        "run-123",
-        [
-          expect.objectContaining({
-            message: expect.objectContaining({
-              params: { entry: secondEntry },
-            }),
-          }),
-          expect.objectContaining({
-            message: expect.objectContaining({
-              params: { entry: thirdEntry },
-            }),
-          }),
-        ],
-        8,
-      );
+        expect(mockTrpcLogs.readLocalLogs.query).toHaveBeenCalledTimes(2);
+      });
+      // Stale fetches can't fill the gap; we must NOT append the snapshot's
+      // tail slice (positions [expectedCount-N, expectedCount]) on top of an
+      // events array that's still at processedLineCount=5 — that path used
+      // to corrupt the array with duplicates/gaps and ratchet
+      // processedLineCount past entries we don't actually have, leading to
+      // unbounded growth on long-running cloud runs.
+      expect(mockSessionStoreSetters.appendEvents).not.toHaveBeenCalled();
     });
     it("flips status to connected on _posthog/run_started", async () => {
       const service = getSessionService();

apps/code/src/renderer/features/sessions/service/service.ts

@@ -3560,23 +3560,18 @@ export class SessionService {
       return;
     }
 
+    // The fetched logs lag behind expectedCount and `newEntries` is the latest
+    // tail slice of the snapshot — appending it here would create duplicates
+    // and gaps in `session.events` (and bump processedLineCount past entries
+    // we don't actually have). Skip; the next snapshot/log update will retry
+    // once the source has caught up.
     log.warn("Cloud task log count inconsistency", {
       taskRunId,
       currentCount,
       expectedCount,
+      fetchedCount: rawEntries.length,
       entriesReceived: newEntries.length,
     });
-    let newEvents = convertStoredEntriesToEvents(newEntries);
-    newEvents = this.filterSkippedPromptEvents(taskRunId, session, newEvents);
-    if (hasSessionPromptEvent(newEvents)) {
-      sessionStoreSetters.clearTailOptimisticItems(taskRunId);
-    }
-    sessionStoreSetters.appendEvents(
-      taskRunId,
-      newEvents,
-      latestCount + newEntries.length,
-    );
-    this.updatePromptStateFromEvents(taskRunId, newEvents);
   }
 
   private createBaseSession(